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International Journal of Computational Engineering Research||Vol, 03||Issue, 5||
Improved Performance for “Color to Gray and Back”
For Orthogonal transforms using Normalization
Dr. H. B. Kekre 1 , Dr. Sudeep D. Thepade 2 , Ratnesh N. Chaturvedi 3
1 Sr. Prof. Computer Engineering Dept., Mukesh Patel School of Technology, Management & Engineering,
NMIMS University, Mumbai, India
2 Professor & Dean (R&D), Pimpri Chinchwad College of Engineering, University of Pune, Pune, India
3 M.Tech (Computer Engineering), Mukesh Patel School of Technology, Management & Engineering, NMIMS
University, Mumbai, India
ABSTRACT:
The paper shows performance comparison of two proposed methods with Image transforms alias
Cosine, Sine, Haar & Walsh using Normalization for „Color to Gray and Back‟. The color information
of the image is embedded into its gray scale version using transform and normalization method. Instead
of using the original color image for storage and transmission, gray image (Gray scale version with
embedded color information) can be used, resulting into better bandwidth or storage utilization. Among
the two algorithms considered the first algorithm give better performance as compared to the second
algorithm. In our experimental results first algorithm for Discreet Cosine Transform (DCT) using
Normalization gives better performance in „Color to gray and Back‟ w.r.t all other transforms in
method 1 and method 2. The intent is to achieve compression of 1/3 and to print color images with
black and white printers and to be able to recover the color information afterwards.
Key Words: Color Embedding; Color-to-Gray Conversion; Transforms; Normalization; Compression.
I. INTRODUCTION
Digital images can be classified roughly to 24 bit color images and 8bit gray images. We have come to
tend to treat colorful images by the development of various kinds of devices. However, there is still much
demand to treat color images as gray images from the viewpoint of running cost, data quantity, etc. We can
convert a color image into a gray image by linear combination of RGB color elements uniquely. Meanwhile, the
inverse problem to find an RGB vector from a luminance value is an ill-posed problem. Therefore, it is
impossible theoretically to completely restore a color image from a gray image. For this problem, recently,
colorization techniques have been proposed [1]-[4]. Those methods can re-store a color image from a gray
image by giving color hints. However, the color of the restored image strongly depends on the color hints given
by a user as an initial condition subjectively.
In recent years, there is increase in the size of databases because of color images. There is need to
reduce the size of data. To reduce the size of color images, information from all individual color components
(color planes) is embedded into a single plane by which gray image is obtained [5][6][7][8]. This also reduces
the bandwidth required to transmit the image over the network.Gray image, which is obtained from color image,
can be printed using a black-and-white printer or transmitted using a conventional fax machine [6]. This gray
image then can be used to retrieve its original color image.
In this paper, we propose two different methods of color-to-gray mapping technique using transforms
and normalization [8][9], that is, our method can recover color images from color embedded gray images with
having almost original color images. In method 1 the color information in normalized form is hidden in HL and
HH area of first component as in figure 1. And in method 2 the color information in normalize form is hidden in
LH and HH area of first component as in figure 1. Normalization is the process where each pixel value is
divided by 256 to minimize the embedding error [9].
The paper is organized as follows. Section 2 describes various transforms. Section 3 presents the
proposed system for “Color to Gray and back”. Section 4 describes experimental results and finally the
concluding remarks are given in section 5.
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